Search results for "Linear"
showing 10 items of 7165 documents
Characteristics of the polymer transport in ratchet systems
2010
Molecules with complex internal structure in time-dependent periodic potentials are studied by using short Rubinstein-Duke model polymers as an example. We extend our earlier work on transport in stochastically varying potentials to cover also deterministic potential switching mechanisms, energetic efficiency and non-uniform charge distributions. We also use currents in the non-equilibrium steady state to identify the dominating mechanisms that lead to polymer transportation and analyze the evolution of the macroscopic state (e.g., total and head-to-head lengths) of the polymers. Several numerical methods are used to solve the master equations and nonlinear optimization problems. The domina…
Estimating the temperature evolution of foodstuffs during freezing with a 3D meshless numerical method
2015
Abstract Freezing processes are characterised by sharp changes in specific heat capacity and thermal conductivity for temperatures close to the freezing point. This leads to strong nonlinearities in the governing PDE that may be difficult to resolve using traditional numerical methods. In this work we present a meshless numerical method, based on a local Hermite radial basis function collocation approach in finite differencing mode, to allow the solution of freezing problems. By introducing a Kirchhoff transformation and solving the governing equations in Kirchhoff space, the strength of nonlinearity is reduced while preserving the structure of the heat equation. In combination with the hig…
Testing experimental designs in liquid chromatography (I): Development and validation of a method for the comprehensive inspection of experimental de…
2020
The basis of interpretive optimisation in liquid chromatography is the prediction of resolution, from appropriate solute retention models. The reliability of the process depends critically on the quality of the experimental design. This work develops, validates and applies a general methodology aimed to evaluate the quality of any training experimental design, which will be applied in Part II to design optimisation. The methodology is based on the systematic evaluation of the uncertainties associated to the prediction of retention times in comprehensive scans of both isocratic and gradient experimental conditions. It is able to evaluate comprehensively experimental designs of arbitrary comp…
Potentialities of microfibers for non linear optics
2010
Micro- and nanofibers present attractive optical properties and may be used in a variety of structures and devices. We report in this work the first global study on the non linear properties of these microfibers: an adequate source is built and its characteristics are described, our first results with a silica loop resonator are presented. Third harmonic generation is obtained in these conditions, however, the low intrinsic non linear index prevents the generation of large non linear effects. The use of highly non linear materials, such as soft glasses, is therefore discussed, with their potentialities and the challenges their integration with standard microfibers represent.
Wronskian representation of solutions of NLS equation, and seventh order rogue wave.
2012
This work is a continuation of a recent paper in which we have constructed a multi-parametric family of the nonlinear Schrodinger equation in terms of wronskians. When we perform a special passage to the limit, we get a family of quasi-rational solutions expressed as a ratio of two determinants. We have already construct Peregrine breathers of orders N=4, 5, 6 in preceding works; we give here the Peregrine breather of order seven.
Nonlinear free vibrations analysis of cracked composite stiffened plates via X-Ritz approach
2019
Thin and moderately thick composite multi-layered plates are widely employed in naval and aerospace structures. They can experience the presence of cracks, generated for example by corrosion, fatigue or accidental external causes, which aect their static and dynamic behaviour. As regard the dynamic characteristics of plates, many studies have focused on the linear vibration analysis of both isotropic and composite thin and thick plates, providing for a comprehensive knowledge of the plate dynamic behaviour. However, for an accurate appraisal of the plate dynamics, in some applications it is needed to investigate the nonlinear free vibration problem; a literature survey evidences that the la…
Multiple Linear Regression to predict larvicidal activity against <em>Aedes aegypti </em>mosquito
2017
Vector-borne diseases are one of the important health problems in most tropical countries. Aedes aegypti is an important vector for transmission of dengue, yellow fever, chikungunya, arthritis, and Zika fever. According to the World Health Organization, it is estimated that Ae. aegypti causes 50 million infections and 25,000 deaths per year. The emerging scenario highlights that the eco-friendly and effective control measures for mosquito vectors is of crucial importance. One of the most effective vector control measures has been the use of larvicidal compounds however; this success was short lived due to development of resistance against them in many mosquito strains, ecological imbalance …
Methods to Compute Pressure and Wall Tension in Fluids containing Hard Particles
2011
Colloidal systems are often modelled as fluids of hard particles (possibly with an additional soft attraction, e.g. caused by polymers also contained in the suspension). in simulations of such systems, the virial theorem cannot be straightforwardly applied to obtain the components of the pressure tensor. In systems confined by walls, it is hence also not straightforward to extract the excess energy due to the wall (the "wall tension") from the pressure tensor anisotropy. A comparative evaluation of several methods to circumvent this problem is presented, using as examples fluids of hard spheres and the Asakura-Oosawa model of colloid-polymer mixtures with a size ratio $q=0.15$ (for which th…
Bounds to internal forces for elastic-plastic solids subjected to variable loads
1979
Considering an elastic-plastic workhardening solid with piecewise linear yield surfaces and a piecewise linear workhardening law, we give a method for constructing bounds to the internal forces and to the (hardened) yield stresses produced by the action of variable loads at any point of the body and at any time. The loading history is supposed to be unknown, but the loads range within a given domain.
Improvement of photo-stability of LLDPE-based nanocomposites
2006
LLDPE-based nanocomposites undergo faster photo-oxidation than the unfilled matrix and the extent of their physical properties deterioration, namely elongation at break and tensile strength, is dependent on the organo-nanoclay loading. The observed acceleration is not due to faster photo-oxidation but rather due to a reduction of the oxidation induction time. The presence in the organoclays of trace amounts of metal ions may be promoting catalytic photodegradation. While UV absorbers provide useful protection, use of a metal deactivator has been found to greatly enhance the photo-stability of the LLDPE-based nanocomposites. Combinations of a metal deactivator and UV absorber yield synergist…